In vitro antiviral activity of dehydroepiandrosterone, 17 synthetic analogs and ERK modulators against herpes simplex virus type 1

► DHEA, EA, three synthetic EA analogs and two synthetic DHEA analogs rendered antiherpetic activity. ► Raf/MEK/ERK signaling pathway modulators can inhibit or enhance viral multiplication. ► DHEA and the synthetic analog E2 may block HSV-1 particle formation and release. ► DHEA’s antiherpetic activity is not due to its Raf/MEK/ERK pathway modulator activity. In the present study the in vitro antiviral activity of dehydroepiandrosterone (DHEA) and 17 synthetic derivatives against herpes simplex type 1 (HSV-1) was determined. DHEA, epiandrosterone (EA), two synthetic DHEA analogs and three synthetic EA analogs showed a selective inhibitory effect on HSV in vitro multiplication. DHEA and E2, a synthetic derivative of EA, were not found to be virucidal to cell-free HSV-1 and did not impair virus adsorption or penetration. We determined that treatment with both compounds decreased viral protein synthesis. Moreover, inhibitory effect of DHEA and E2 on extracellular viral titer was stronger than the inhibition found on total viral infectivity, suggesting that the antiherpetic activity of these compounds may also be in part due to an inhibition in virus formation and release. Since DHEA is a known Raf/MEK/ERK signaling pathway activator, we studied the role of this pathway on HSV-1 infection. ERK1/2 phosphorylation was stimulated in HSV-1 infected cultures. UO126, a Raf/MEK/ERK signaling pathway inhibitor, impaired viral multiplication, while anisomycin, an activator of this pathway, enhanced it. Treatment with DHEA 6h before infection enhanced HSV-1 multiplication. On the contrary, pre-treatment with E2, which does not modulate Raf/MEK/ERK signaling pathway, did not produce an increase of viral replication. Taking together these results, the antiviral activity of DHEA seems to occur via a mechanism independent of its ability to modulate ERK phosphorylation.